1. Field
The present disclosure relates generally to printed circuit board assemblies (“PCBAs”) and electromagnetic interference (“EMI”) shields.
2. Description of the Related Art
There are many instances where a PCBA, which includes a printed circuit board (“PCB”) and electronic components mounted on the PCB, is combined with an EMI shield to form a PCB apparatus. For example, sound processors employed in cochlear implant systems may include such a PCB apparatus. The EMI shield prevents electromagnetic emissions generated by the electronic components on the PCB from interfering with other electronic components on the PCB. The EMI shield may also be used to prevent electromagnetic emissions from emanating beyond the PCB apparatus, and to prevent externally generated electromagnetic emissions from interfering with the electronic components of the PCB apparatus.
Some conventional EMI shields consist of one or more EMI containment enclosures that are secured to the PCBA over the electronic components. The present inventor has determined that such containment enclosures, while effective, tend to increase the size of the PCB apparatus and also add to component costs and assembly costs. Other conventional EMI shields consist of an electrically insulating coating that is applied to the PCBA and an electrically conductive coating that is applied over the insulating coating. The present inventor has determined that conventional coating-based methods are susceptible to improvement. For example, the present inventor has determined that conventional coating-based EMI shields are not well suited for use with three-dimensional PCBAs because the employed insulating coatings may crack when the PCBA is folded into the three-dimensional shape, which can lead to shorts, and the employed electrically conductive coatings are thin, solvent-based materials that will not properly fill the internal volume defined by the folded PCBA.